P0440
PowertrainEvap Systemlow severityEvaporative Emission Control System Malfunction
What P0440 Means
General EVAP system malfunction. The EVAP system captures fuel vapors and prevents them from escaping to the atmosphere.
Symptoms
- Check Engine Light
- Fuel smell
- Failed emissions test
Common Causes
- Loose or missing gas cap (most common)
- Cracked EVAP hose
- Faulty purge valve
- Faulty vent valve
- Charcoal canister saturated
- Leak in fuel tank or filler neck
Diagnostic Steps
- Check gas cap seal and tighten
- Perform EVAP smoke test
- Test purge valve
- Test vent valve
- Check EVAP hoses
- Inspect charcoal canister
Where to start: Start with gas cap - tighten and clear code. If returns, smoke test the EVAP system.
🔌 Don't have a code reader?
Any of these will read and clear this code — pick by how deep you want to go.
Budget handheld~$40
ANCEL AD410 →
No-phone-needed handheld — reads, clears, live data, freeze frame.
✓ ANCEL official store
Serious DIY~$100
BlueDriver Pro →
Enhanced codes (ABS, airbag, TPMS) plus repair reports.
SHOP FAVORITEShop-grade tablet~$300
Autel MaxiCOM MK808S →
Bidirectional tests, service resets, all systems.
✓ Autel official store
Pro diagnostics$1,500+
Autel MaxiSys MS906 Pro →
Full-system pro platform — topology mapping, ECU coding, the works.
✓ Autel official store
As an Amazon Associate and Autel/ANCEL partner, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.
Related Codes
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